Retroperitoneal primitive neuroectodermal tumour (PNET). A case report and review of the literature

Practical Management of Adult Ultra-Rare Primary Retroperitoneal Soft Tissue Sarcoma: A Focus on Perivascular Epithelioid Tumours and Extraosseous Ewing Sarcoma

With the exception of well-differentiated liposarcoma, dedifferentiated liposarcoma, leiomyosarcoma, solitary fibrous tumour, malignant peripheral nerve sheath tumour, and undifferentiated pleomorphic sarcoma, the majority of the ≈70 histologic subtypes of retroperitoneal sarcoma are defined as 'ultra-rare' sarcomas, with an incidence of ≤1-5/1,000,000 persons/year. For most of these ultra-rare RPS subtypes, diagnosis and treatment follows international guidelines for the management of more common RPS histologies, with en bloc surgical resection as the mainstay of curative treatment, and enrolment in clinical trials where possible. Because the treatment of RPS is heavily driven by histology, the surgeon must be familiar with specific issues related to the diagnosis and management of ultra-rare sarcoma subtypes. Expert radiological and surgeon reviews are required to differentiate similarly presenting tumours where surgery can be avoided (e.g., angiomyolipoma), or where upfront systemic therapy is indicated (e.g., extraosseous Ewing's sarcoma). Thus, the management of all retroperitoneal sarcomas should occur at a sarcoma referral centre, with a multidisciplinary team of experts dedicated to the surgical and medical management of these rare tumours. In this focused review, we highlight how diagnosis and management of the ultra-rare primary RPS histologies of malignant perivascular epithelioid cell tumour (PEComa), extraosseous Ewing sarcoma (EES), extraosseous osteosarcoma (EOS), and rhabdomyosarcoma (RMS) critically diverge from the management of more common RPS subtypes.

A rare case of retroperitoneal primitive neuroectodermal tumor (PNET)

Retroperitoneal primitive neuroectodermal tumors (PNET) is a rare neoplastic disease of high malignancy with a tendency towards early metastasis, affect young adults irrespective of the gender. We present 81 year old woman, who was admitted in the Urology Department with symptoms of right flank pain and hematuria. Contrast-enhanced computerized tomography scan (CT-scan) showed a large heterogeneous right kidney mass around 12 cm in diameter. The final diagnosis of primitive neuroectodermal tumor (PNET) was established based on clinical, pathological, and molecular results.

Outcome of multidisciplinary treatment of peripheral primitive neuroectodermal tumor

Peripheral primitive neuroectodermal tumors (PNETs) constitute very rare and aggressive malignancies. To date, there are no standard guidelines for management of peripheral PNETs due to the paucity of cases arising in various body sites. Therapeutic approach is derived from Ewing sarcoma family, which currently remains multimodal. Our study retrospectively analyzed 86 PNET patients from February 1, 1998 to February 1, 2018 at Peking Union Medical College Hospital with an additional 75 patients from review of literature. The clinicopathologic and treatment plans associated with survival was investigated. Surgery, chemotherapy, female sex, small tumor size, no lymph node metastasis, R0 surgical resection, (vincristine + doxorubicin + cyclophosphamide)/(isophosphamide + etoposide) regimen, and more than 10 cycles of chemotherapy were associated with improved overall survival in univariate analysis. Surgery, more than 10 cycles of chemotherapy, and small tumor size were independent prognostic factors for higher overall survival. Our data indicates that multimodal therapy is the mainstay therapeutic approach for peripheral PNET.

Retroperitoneal extraosseous peripheral primitive neuroectodermal tumor in a Formosan serow: case report and literature review

A 10-y-old female captive Formosan serow (Capricornis swinhoei) was inactive and was azotemic. An autopsy was performed following her death, and multiple irregularly shaped, white-to-gray masses of 0.5-2 cm diameter were noted on both ureters, the left adrenal gland, urinary bladder, and uterus. Microscopically, organs were effaced by a poorly demarcated, highly infiltrative neoplasm, composed of neoplastic round cells arranged in islands, sheets, or nests with occasional rosette formation. The neoplastic cells were small: ≤2 red blood cell (≤ 15 μm) diameter. The neoplastic cells were positive for CD56, CK, FLI-1, and NSE, but negative for desmin, GFAP, melan A, NF, PAX-8, S100, synaptophysin, and vimentin. Therefore, the diagnosis of retroperitoneal extraosseous peripheral primitive neuroectodermal tumor (pPNET) was made. pPNET with FLI-1 expression has not been reported previously in animals, to our knowledge.

Long-term survival of a patient with a large adrenal primitive neuroectodermal tumor: A case report

BACKGROUND

Adrenal primitive neuroectodermal tumor (PNET) is an extremely rare malignant tumor with poor prognosis and of neural crest origin. Herein, we report a case of adrenal PNET and summarized its clinical and pathological characteristics on the basis of 16 patients reported recently.

CASE SUMMARY

A female patient aged 25 years presented with right lumbago for 12 mo, and pre-operative computed tomography showed a huge right adrenal mass. She received tumorectomy, and post-operative pathological examination showed adrenal PNET. After surgery, she underwent adjuvant chemotherapy and was followed up 31 mo after surgery. She received brachytherapy for right paracolic and hepatic metastases. She was alive and followed up for 60 mo. In available studies, only 57.14% (4/7) and 44.44% (4/9) were positive for the expression of neuron-specific enolase and synaptophysin, respectively, although CD99 expression was found in all the patients (100%; 10/10).

CONCLUSION

It is concluded that adrenal PNET is very rare and highly malignant, and histology is a golden standard in its diagnosis. Surgery and adjuvant therapy is the main treatment.

Primitive neuroectodermal tumors of adrenal gland

OBJECTIVES

To analyze the clinical and pathological characteristics of adrenal primitive neuroectodermal tumors for a better understanding of the disease.

METHODS

A retrospective analysis of four cases of adrenal primitive neuroectodermal tumors (two male, two female; age 21-30, average 24) was made. All patients went through necessary endocrinological exams, computer tomography scans (for site-specific diagnoses) and pathological tests.

RESULTS

No positive result was reported in routine laboratory tests and endocrinological exams. Computer tomography scans showed bulk soft tissue masses with rough borders. The masses were 8-17 cm in diameter with solid-cystic changes. Among the four patients, one refused to receive treatment after definitiver diagnosis through needle biopsy, three received surgical treatments and their post-operative pathological exams all confirmed the diagnoses of primitive neuroectodermal tumors. During the follow-ups, the untreated patient died 6 months afterwards, one patient died 8 months after palliative treatment; one patient showed distant metastasis 13 months after surgery and did not respond well to both radio- and chemotherapy; one patient had local recurrence 1 month after surgery and is presently undergoing chemotherapy.

CONCLUSIONS

Adrenal primitive neuroectodermal tumor is a very rare tumor. It originates in primitive neuroectoderma and is found mainly in 20-30-year-old young populations. It has non-specific clinical or imaging manifestation and its diagnosis is mostly based on pathological examinations. The tumor is fast-developing, highly malignant with poor prognosis.